You are already on the highest system menu version available so far. While we never recommend updating, I doubt it would do much harm on your unmodded wii.
You can follow that softmod guide and use it to allow for backup playing, but the black wii console has a new drivechip that won't allow you to use disks for backups. You will have to use usb devices (harddrive or flash drive) to play backups. Everything you need to mod is in that guide and there are guides to setup your usb devices.
There is also a guide for explaining what a cios and ios's are in the guides section.